1T2W,1T2O,2KID,1T2P,1IJA,2MLM,2KW8,4O8L,4O8T,4TQX,3RCC,3FN6,3FN7,3FN5


Conserved Protein Domain Family
Sortase_A

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cd06165: Sortase_A 
Click on image for an interactive view with Cn3D
Sortase domain found in class A sortases
Class A sortases are membrane-bound cysteine transpeptidases distributed in Gram-positive bacteria (mainly present in Firmicutes). They perform a housekeeping role in the cell as members of this group are capable of anchoring a large number of functionally distinct surface proteins containing a cell wall sorting signal to an amino group located on the bacterial cell wall. They do so by catalyzing a transpeptidation reaction in which the surface protein substrate is cleaved at a conserved cell wall-sorting signal (Class A sortases recognize a canonical LPXTG motif, X can be any amino acid), and covalently linked to peptidoglycan for display on the bacterial surface. The prototypical sortase A protein from Staphylococcus aureus (named Sa-SrtA) cleaves the amide bond between threonine and glycine residues of the canonical LPXTG motif in a wide range of protein substrates with diverse functions that can promote bacterial adhesion, nutrient acquisition, host cell invasion, and immune evasion. Next, it catalyzes a transpeptidation reaction by which the proteins are covalently linked to the peptidoglycan precursor lipid II. SrtA is therefore affects the ability of a pathogen to establish successful infection. SrtA contains an N-terminal hydrophobic segment, a linker region and an extra-cellular C-terminal catalytic domain. The hydrophobic segment functions as both a signal peptide for secretion and a stop-transfer signal for membrane anchoring. The catalytic domain contains the catalytic TLXTC signature sequence where X is usually a valine, isoleucine or a threonine. The gene encoding SrtA is generally not located in the same gene cluster as its substrates while the gene encoding SrtB is usually clustered in the same locus as its substrate.
Statistics
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PSSM-Id: 320680
View PSSM: cd06165
Aligned: 189 rows
Threshold Bit Score: 96.4181
Threshold Setting Gi: 81667644
Created: 14-May-2008
Updated: 18-Aug-2016
Structure
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Program:
Drawing:
Aligned Rows:
 
Conserved site includes 3 residues -Click on image for an interactive view with Cn3D
Feature 1:catalytic site [active site]
Evidence:
  • Comment:The SrtA enzymes recognize a conserved five amino acid sequence (LPXTG) at the C-terminus of their protein substrates and cleave the amide bond between the threonine and glycine residues using a highly-conserved cysteine residue in the active site. Two other active site residues have been identified as essential for optimal enzyme activity, a His side-chain which serves as a general base and an Arg side-chain which stabilises the oxoanion intermediate formed during the reaction.
  • Comment:The catalytic triad is formed by His, Cys, and Arg. The sulfhydryl of Cys is ionized by His and the resultant thiolate attacks the LPXTG peptide.

Sequence Alignment
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Format: Row Display: Color Bits: Type Selection:
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1                                                           #                            
1T2W_A         9 SKVAGYIEIPdaDIKEPVYPGpATPEQLNrGVSFAEenes-lddQNISIAGHTFidr--pnyQFTNLKAAk-kGSMVYFK 84
gi 548582916  86 QWAIGVLSIPsvAVDQPVLAG-MTETNLLnGVATYNaker-mgqGNFILSSHNMvga---emLLNPISGVq-aGAPIYLT 159
gi 654318719  85 QQAIGLVCIPaaKIILPIFPG-TSDFALLnGVGTYWrnqr-lgqGNYVVAAHNLsgq---kaLLNPMTAVk-pGQHIYLT 158
gi 919169652  98 KSMIGQLTIPsvHINLPVFSG-MSNAALLnGVGTFSkkrs-mgqGNFVMMAHNLpaqy-sdaLLQPLSQIk-pKAKIRIT 173
gi 972558416  88 LDVLGAVAIPdaNLNTAVIKG-MSDVAMVsGAGTMFpdqv-mgqGNYTLASHHIgyg--tdiLLNNISDSvtvGDKIYLT 163
gi 515408782  88 LDILGAVAIPdaNLNTTVIKG-LSDAAMVsGAGTMFpdqv-mgqGNYALASHHIgyg--tdiLLNNISDSvtvGDKIYLT 163
gi 987323402  60 LDIKGALVYPnaHIYGPLVEG-LTEENMHyGIATFYpdeqilgeGNYPVTSHNIdyfk-kgvLLSPIVTEakiGDLVYVT 137
gi 984721185   2 IPVIGAVAYPdaDIYVPIFDG-LTEENMLhGASTFFpgeqklgqGNYPITSHNMnyfg-enlLLTPILDKtkmGDSIYVT 79
gi 984720655  85 VNVIGALAMPdaDVKVSIMKG-LSEDVLLsGAGTFYpeqk-mgeGNYPLASHNMnvvq-kglLLSPIVDKaqvGQKIYMT 161
gi 543978859  99 NNAIGAIHIPnqKIRLAVLHG-VNDTIMFaGAGTLSpyqv-mgqNNFPLISHKLylsqdqnlLFNQIENVe-mGSIIRLT 175
                         90       100       110       120       130       140
                 ....*....|....*....|....*....|....*....|....*....|....*....|..
Feature 1                                                  #            #      
1T2W_A        85 VgNETRKYKMTSIRDVKPtdvGVLDEQkg----kDKQLTLITADdynektgvWEKRKIFVAT 142
gi 548582916 160 DwRRVYVYKATVNQVVDEhaiQYLAQPrt----gQPVVTLMRCSgg----ydTPYRRIVQGR 213
gi 654318719 159 DfVHLATYTAVSNRVVTDrhsELLAVPgp---hqPAEVTLFRCVgg----igTPWREVLQGR 213
gi 919169652 174 DfNNVYTYEASYKNIVDSsniKLLGQTh------KSIVTLFRCVge----hgTNNRLIVQGN 225
gi 972558416 164 DlTNVYVYETFFVEAVNPdqvQYISQEvt----gNPIITLMTCTa------dLTQRWIVQGN 215
gi 515408782 164 DlTNVYVYETFFVEAVNPdqvQYISQEvt----gNPIITLMTCTa------dLTQRWIVQGN 215
gi 987323402 138 DlQNIYTFKVDFNETVPEtrvDLVETNw-----dHPILTMMTCSkpv---qpVHTRKIVQAS 191
gi 984721185  80 DlDKIYRFEVDFNEVVPEtrvDLVDPKt-----dQAMLTLMTCTkal---gdDPNRKIVQAK 133
gi 984720655 162 DlEKIYIYDTFFVEDVPPtrvDLVDPNlldpetqKPIITLMTCTd------dATERRIVQGR 217
gi 543978859 176 DlETIWEYKAYDFIKIDEknvDAVDPFktg-pngKPIISLVTCVay-----gEPSRYVLYGE 231

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